The MBS is a point-to-multipoint transmission scheme for concurrent transport of data packets from a source to a plurality of destinations. A broadcast service is a service where data packets are transmitted to all users, and a multicast service is a service where data packets are transmitted to users belonging to a specific group.
A terminal receives an MBS configuration message from a base station, and acquires information on an MBS MAP. The terminal receives and decodes the MBS MAP representing information on MBS burst data based on the information on the MBS MAP. The terminal acquires information on bursts corresponding to MBS contents based on the MBS MAP, and receives and decodes the bursts.
The MBS configuration message has a lifetime, and does not change during the lifetime. Accordingly, when the lifetime expires and the MBS configuration message changes, the terminal should receive the MBS configuration message again. In the case that the MBS configuration message does not change when the lifetime expires, the terminal maintains information of the MBS configuration message with the stored values. Further, the terminal resets the lifetime to an initial value, and a timer restarts. The MBS MAP provides information on whether the MBS configuration message changes or not.
Whenever the MBS configuration message is transmitted, it is transmitted with the counted down value of the previous lifetime. Accordingly, the terminal cannot acquire an exact lifetime in accordance with a time when the terminal joins the MBS. In this case, if the lifetime expires and any information of the MBS configuration message does not change, the terminal cannot reset the lifetime to the exact value when resetting the lifetime.